The fuel tank of a motor vehicle is filled with fuel via a fuel filler pipe extending between an externally accessible location of the motor vehicle and the fuel tank, wherein fueling is accomplished by a user inserting a service station fuel pump nozzle into the fuel filler pipe.
As can be understood by reference to FIG. 1, the fuel filler pipe 10 includes a filler tube 12 connected to (at least one) fuel tank 14, a nozzle entry chamber 16 which has a generally cylindrical shape of a diameter much larger than that of the filler tube, and a filler neck 18 which has a generally frustoconical shape that provides interfacing between the filler tube and the nozzle entry chamber. The nozzle entry chamber 16 has a threaded opening 20 for threadably receiving a selectively removable filler cap (sometimes referred to as a “gas cap”) 22 and further has a nozzle guide orifice 24 internally disposed in the nozzle entry chamber in spaced relation with respect to the threaded opening. The fuel filler pipe 10 is interfaced with the vehicular body 26 by connection thereto at the nozzle entry chamber 16. The fuel filler pipe 10 may be formed of metal, plastic or other suitable material. 
In operation, a service station customer unthreads the filler cap 22, inserts the service station fuel pump nozzle 28 into the nozzle entry chamber 16 so that it passes through the nozzle guide orifice 24, and then begins fueling the motor vehicle. The fueling process is automatically regulated by a fuel shut-off sensor 30 in the pump nozzle. The fuel shut-off sensor 30 senses predetermined differential pressure between the fluid pressure of fuel exiting the pump nozzle 28 and the fluid pressure at an aspirator hole 32 in the pump nozzle so that fuel flow will be automatically shut-off before the fuel can accumulate sufficiently such as to overflow the fuel filler pipe.
Problematically, the fuel shut-off sensor can cause premature shut-off (PSO) of fuel flow from the pump nozzle at any time during the fueling process, even at the initial stage thereof, if an erroneous differential fluid pressure between the aspirator hole and the fuel exiting the pump nozzle is sensed by the fuel shut-off sensor. This can happen if the aspirator hole 32 is obstructed or if there is a reverse circulation of the fuel due to the fuel exiting the pump nozzle in a non-axial direction such that fuel incidentally (glancingly) strikes upon the inner surface 34a of the sidewall 34 of the fuel filler pipe 10. PSO is quite annoying to the service station customer, and can be even more so in the event PSO causes fuel to be undesireably spit from the nozzle entry chamber.
FIGS. 2A through 2C depict examples of the above mentioned causes of PSO. In FIG. 2A, the aspirator hole 32 of the fuel shut-off sensor 28 is obstructed because the aspirator hole location of the pump nozzle 28 is touching the inner surface 34a of the fuel filler pipe 10 at a nozzle engagement zone 36 of the filler neck 18. In FIG. 2B, a nozzle end portion 28a of the pump nozzle 28 is tilted out of axial alignment with the filler neck 18 at the nozzle engagement zone 36. The tilt of the nozzle end portion 28a results in the aspirator hole 32 being subjected to increased fluid pressure inducing PSO because of the fuel flow F exiting the nozzle is non-axial, resulting in the fuel incidentally (glancingly) striking upon the inner surface 34a, which, in turn, results in a fuel flow reverse circulation F′. The reverse  fuel circulation causes pressure at the aspirator hole to be undesireably sensed as higher than if reverse fuel circulation was not present. In FIG. 2C, the tilt of the nozzle end portion 28a of the pump nozzle 28 at the nozzle engagement zone 36 is now opposite to that shown in FIG. 2B, wherein the aspirator hole 32 is now subject to low pressure, which causes PSO. This arises because the reverse fluid flow F′ (which, as described immediately above, occurs because of non-axial fluid flow from the pump nozzle) causes an untoward increase in the pressure of the fuel exiting the pump nozzle, and in differential relation thereto, the fluid pressure sensed at the aspirator hole is artificially low because of venturi effects.
Accordingly, what remains needed in the art is some way to locate the pump nozzle of a service station fuel pump so that the automatic fuel shut-off sensor of the pump nozzle functions properly and without premature shut-off.